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>ioctl VIDIOC_ENUMAUDIO</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8246"
></A
><H2
>Name</H2
>VIDIOC_ENUMAUDIO&nbsp;--&nbsp;Enumerate audio inputs</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8249"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><P
></P
><A
NAME="AEN8250"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, struct v4l2_audio *argp);</CODE
></P
><P
></P
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><DIV
CLASS="REFSECT1"
><A
NAME="AEN8260"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="PARAMETER"
>fd</CODE
></DT
><DD
><P
>File descriptor returned by <A
HREF="r14090.htm"
><CODE
CLASS="FUNCTION"
>open()</CODE
></A
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>request</CODE
></DT
><DD
><P
>VIDIOC_ENUMAUDIO</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>argp</CODE
></DT
><DD
><P
></P
></DD
></DL
></DIV
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><DIV
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><A
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></A
><H2
>Description</H2
><P
>To query the attributes of an audio input applications
initialize the <CODE
CLASS="STRUCTFIELD"
>index</CODE
> field and zero out the
<CODE
CLASS="STRUCTFIELD"
>reserved</CODE
> array of a struct&nbsp;<A
HREF="r9539.htm#V4L2-AUDIO"
>v4l2_audio</A
>
and call the <CODE
CLASS="CONSTANT"
>VIDIOC_ENUMAUDIO</CODE
> ioctl with a pointer
to this structure. Drivers fill the rest of the structure or return an
<SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
> error code when the index is out of bounds. To enumerate all audio
inputs applications shall begin at index zero, incrementing by one
until the driver returns <SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
>.</P
><P
>See <A
HREF="r9539.htm"
>ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO(2)</A
> for a description of
struct&nbsp;<A
HREF="r9539.htm#V4L2-AUDIO"
>v4l2_audio</A
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8292"
></A
><H2
>Return Value</H2
><P
>On success <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> is returned, on error <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set appropriately:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>The number of the audio input is out of bounds, or
there are no audio inputs at all and this ioctl is not
supported.</P
></DD
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